Anthropogenic (Man Made Material)

Chert (Agatized/Chalcedony variety)

Microcrystalline Quartz (SiO2)

Chert Nodule in Limestone

Silicon Dioxide (SiO2) in Calcium Carbonate (CaCO3)

Limonite with Trace Fossils

Hydrous Iron Oxide Mixture (FeO(OH)·nH2O)

Chert (containing Flint nodules)

Microcrystalline or cryptocrystalline Quartz (SiO2)

Chert Concretion with Iron Oxide Staining

Microcrystalline Quartz (SiO2)

Quartz (Small Pebble)

Silicon Dioxide (SiO2)

Chert Nodule

Microcrystalline Quartz (SiO2)

Chert (Jasper)

Silicon Dioxide (SiO2)

Picture Jasper

SiO2

Fossil coral (likely solitary rugose coral)

Rugosa; possibly genus Heliophyllum or similar

Chert Nodule / Flint

Microcrystalline Quartz (SiO2)

Sandstone (Red/Brown Sandstone pebble)

Arenite (SiO2 dominated sandstone)

Likely weathered iron-rich stone

Uncertain; possibly limonite/goethite-bearing rock

Iron-stained quartzite or quartz-rich sandstone

Quartzite, predominantly SiO₂, with iron-oxide staining

Basaltic volcanic pebble

Fine-grained mafic igneous rock, chiefly plagioclase and pyroxene, commonly with olivine and iron-titanium oxides

Chert (Flint)

Microcrystalline Quartz (SiO2)

Chert (Flinty variety)

Microcrystalline Quartz (SiO2)

Laterite

Laterite (primarily composed of hydrated oxides of iron and aluminum)

Tumbled orange chalcedony or jasper

Microcrystalline quartz (SiO₂), likely iron-stained chalcedony/jasper

Tektite (Indochinite)

Natural glass (High-silica impact glass)

Weathered fossiliferous limestone pebble

Calcitic limestone, predominantly CaCO₃ (likely containing fossil or bioclast fragments)

Iron-stained quartz-rich rock, possibly jasper/quartzite

Quartz (SiO₂) with iron-oxide staining; likely ferruginous quartzite or jasper

Small polished pink-and-white mineral pebble

Likely rose quartz or pale pink quartz; exact identification is uncertain from the image

Polished ocean jasper (orbicular jasper), probable

Microcrystalline quartz (SiO₂), chiefly chalcedony with iron-oxide and other mineral inclusions

Tumbled brown quartz/chalcedony (probable)

Quartz, SiO₂; possibly brown chalcedony or jasper

Quartz geode clusters

Microcrystalline quartz (SiO₂), with possible chalcedony and minor iron-oxide staining

Weathered basaltic rock fragment

Basalt, likely porphyritic or amygdaloidal basalt with weathered iron-oxide-rich zones

Orange chalcedony (likely carnelian)

Microcrystalline quartz, SiO₂; iron-bearing chalcedony (carnelian)

Orbicular rhyolite (likely)

Rhyolite, a silica-rich volcanic rock; commonly quartz, alkali feldspar, plagioclase, and iron-rich alteration minerals

Quartz-rich pegmatite with mica and dark inclusions

Pegmatite; chiefly quartz (SiO₂), with feldspar and biotite/tourmaline inclusions

Polished/tumbled calcite

Calcite (calcium carbonate, CaCO₃)

Red jasper (likely brecciated jasper)

Microcrystalline quartz/chalcedony, SiO₂, colored mainly by iron oxides

Chert Nodule / Flint

Microcrystalline Quartz (SiO2)

Red Sandstone

Arenite (typically with iron oxide/hematite cement)

Fossiliferous Limestone

Calcium Carbonate (CaCO3) with Bioclasts

Red Sandstone

Arenite (SiO2 based with Fe2O3)

Quartz (Small fragments)

Silicon Dioxide (SiO2)

Chert (Black Chert or Flint)

Silicon Dioxide (SiO2)

Chert Nodule (Flint)

Chert (Cryptocrystalline Silica - SiO2)

Chert (Flint)

Silicon Dioxide (SiO2)

Chert (Flint)

Microcrystalline Quartz (SiO2)

Black jade or dark serpentine cabochon

Jadeite (NaAlSi₂O₆) or nephrite amphibole; possibly serpentine (Mg₃Si₂O₅(OH)₄)